1. Field of the Invention
The invention relates to a hydraulic operating apparatus, especially for a vehicle covering, having a reversible pump which, via hydraulic lines, one of which is in all cases provided with an unblockable check valve, is connected with the working chambers of at least one double-acting piston-cylinder arrangement.
2. The Prior Art
AT 396.613 discloses an operating apparatus for vehicle coverings wherein the valve-stem side and piston side working chambers of two piston-cylinder arrangements are controlled from both outlets of a reversible pump in order to extend and pull in the covering. The different volumes are balanced out from the reservoir of the hydraulic medium as controlled via a change-over valve. For achieving an emergency stopping function which, depending on demand, can be provided on one or also on both sides, a check valve is employed in one of the hydraulic line. This check valve is unblocked by the pressure in the system at normal operation.
In addition to the operation of the covering itself, an automatic operation of the covering of the cover and/or of its locking mechanism is increasingly desired. For this purpose, further piston-cylinder arrangements are provided which are either supplied via an additional, separate hydraulic circle or are controlled by the main pump of the system via suitable line, valve and control arrangements and the like. Both variants require a relatively large constructive and control-technical effort and increase both the weight and cost of the device.
Thus the object of the present invention is to provide a hydraulic operating apparatus of the above-mentioned type with which, in a simple manner and with a minimum of constructive and control-technical effort, a flexible supply and control of mutually independently operated piston-cylinder arrangements is possible.